Brief summaries of tropical Atlantic activity tailored to the general public, coastal residents, and weather enthusiasts. I have been sending out these updates since 1996, and appreciate everyone's continued interest!

30 September 2010

Since my update on Tuesday, TD16 was briefly upgraded to TS Nicole, then Nicole rapidly lost its tropical characteristics and merged with a mid-latitude trough... before even reaching Florida! This was a very unusual situation, and is resulting in a very unusual heavy rain event up the entire US east coast. Everywhere from FL to ME and from the coast to hundreds of miles inland, flooding rains are the big story.
See http://www.weather.gov/largemap.php for a real-time summary of the watches and warnings associated with this event, and http://www.hpc.ncep.noaa.gov/discussions/nfdscc5.html for a history of what has fallen so far in select locations.

Elsewhere, there's a broad circulation associated with an (possibly 2 really close) easterly wave located about 800 miles east of the Windward Islands. Though not widely favored by global models for development, it looks fairly impressive on satellite imagery.

29 September 2010

During the last three days since my last update, Lisa and Matthew fizzled out (Lisa drifted north over cold water in the far eastern Atlantic and Matthew dumped ridiculous amounts of rain over much of central America and dissipated inland), and a new large area of disturbed weather has been brewing over the western Caribbean... perhaps the one that many of the global models hinted at over a week ago.

That disturbance was upgraded to TD16 today at 15Z based on satellite and surface observations... and a recon aircraft just took off for a flight into the system as I type this. The intensity estimate is 30kts and 1001mb; it's located about 180 miles S of Havana and tracking NNE at 9kts. It is forecast to slowly intensify and head NNE, bringing it over Cuba then into south Florida most likely as a TS. There are Tropical Storm Warnings for central Cuba, the Bahamas, and the Florida peninsula from Key West to West Palm Beach. The next name on the list is Nicole.

23 September 2010

Lisa has been plagued by a hostile environment with moderately strong vertical shear and moderately dry low-mid level air... a bad combination if you're a tropical cyclone. As a result the storm was downgraded to a Depression at 09Z today, and remains so at 15Z. However, there is a 1-2 day window of opportunity beginning now where the environment should improve before drier air invades again. Regardless, Lisa will remain a weak storm and far from any land.

On the other hand, that area of disturbed weather that was skimming the Venezuelan coast the past couple of days is now located north of western Columbia and heading west toward Nicaragua. The environment in which this system is embedded couldn't be any more conducive for significant development: 30C SSTs, 5 kts of vertical shear, and huge values of ocean heat content. Though it has taken nearly a week to get spun up (not out of the norm), it appears that it is now nearly a Depression and could quickly intensify to TS Matthew. As I mentioned before, a system like this must be watched very closely, because it WILL affect land, and probably have 1-3 landfalls in its lifetime. I've been perusing the global model output regularly, and an overall trend and consensus is to bring the storm gradually WNW through much of the western Caribbean, then perhaps a NW turn to bring it up into the Yucatan Straights area by the middle of next week.
A recon plane left St. Croix early today and is conducting multiple penetrations through the system as I type this. So far, a central pressure of 1008mb has been found, along with 36kt flight-level winds (corresponds to nearly tropical storm force at the surface).

21 September 2010

Igor is still officially a hurricane, though is in the midst of its extra-tropical transition. Storms like this that are over very cold SSTs (15F) and in 50kts of vertical shear can still be very powerful thanks to baroclinic enhancement. The same trough that's steering and shearing it is providing an energy transfer to the dying [formerly-barotropic] hurricane. Here's one model's (HWRF) representation of an along-shear vertical cross-section of the storm showing a barely barotropic structure: http://einstein.atmos.colostate.edu/~mcnoldy/tropics/hwrf/2010/plots/AL11/2010AL11_HWRFXSEC_201009210600_F000.PNG

At 15Z, Igor's intensity was 65kts, 952mb, and cruising by Newfoundland at 40kts. It probably has another 6-12 hours remaining as a system that NHC tracks. It has been a hurricane for nearly 10 days and using NTC as a measure of seasonal activity, has provided ~40% of a typical season's entire activity by itself (NTC is Net Tropical Cyclone activity which combines the numbers and longevities of the various storm intensities --TS, H, MH-- and compares them to climatology)!

At 03Z today, the easterly wave in the far eastern Atlantic was upgraded to TD14, then six hours later, to TS Lisa, the 12th named storm of the season. It's located about 530 miles WNW of the Cape Verde islands, and drifting to the north. It is forecast to continue drifting to the north, and only intensify slightly, probably never reaching hurricane status and never affecting any land.

Back on the 16th, I mentioned a "suspicious surge of southwesterlies" about 1700 miles east of the Lesser Antilles. Well, it has indeed festered for a few days, and is now a fairly impressive disturbance located just north of the central Venezuelan coast. Conditions are favorable for further (and significant) development, so this will be watched very closely. The next name on the list is Matthew.

20 September 2010

Hurricane Igor made its closest to Bermuda right around midnight local time as forecast. A peak wind of 81kts was reported on the island, and the minimum pressure at that time was 955mb. The radar loop showing the approach is here: http://einstein.atmos.colostate.edu/~mcnoldy/tropics/igor10/Igor_19-20Sep10.gif (the radar and/or network was down on Bermuda as the eyewall neared, so the loop cuts off just prior to closest approach).
At 15Z today, the intensity was 65kts (minimal hurricane) and 960mb. Tropical storm force winds extend 300 miles to the NE and NW of the center, and 12' seas extend out to 800 miles from the center in the southwest quadrant. A tropical storm warning is now in effect for eastern Newfoundland, but by Tuesday morning, the long-lived (12 days) powerful hurricane will begin its extra-tropical transition as it merges with a mid-latitude trough.

The final advisories were written on Karl and Julia on Saturday 09Z and Monday 15Z, respectively.

The easterly wave that I mentioned on Friday has continued to get better organized and now has a 1007mb Low associated with it. It's located about 450 miles west of the Cape Verde islands and drifting to the NW. There's also an easterly wave right on the African coast. Both of these will be watched closely, and the next names are Lisa and Matthew.

Julia has been slow to weaken, but is now estimated to be 75kts and 981mb. It's been moving quite a bit further west than expected, and the relatively tiny storm is only about 800 miles due east of Igor and it's huge circulation. The forecast is for continued weakening and a turn to the NW then recurving by 55W.

2010 is shaping up to be quite a historic season... during the overnight hours, Karl rapidly intensified to 105kts, making it the fifth major hurricane of the season, and the furthest south a major hurricane has ever existed in the Gulf of Mexico. It also made a turn to the WSW, steering it directly into the city of Vera Cruz (Mexico's oldest and largest port with a population of ~ 700,000 and 490 years of history). The city has never experienced a major hurricane, so this will probably be quite destructive and worthy of retiring the name Karl (which has been in rotation since the beginning of naming hurricanes)! Only 3 other "K" storms have been retired: Klaus '90, Keith '00, and Katrina '05. As I type this message, Karl is making landfall with an intensity of 105kts and a central pressure of 967mb. Not only will the powerful winds be destructive, but flooding rains (up to 15" forecast) and a significant 12-15' storm surge. There is a radar loop of Karl here: http://einstein.atmos.colostate.edu/~mcnoldy/tropics/karl10/Karl_16-17Sep10.gif showing an eyewall replacement cycle, subsequent eyewall contraction, and landfall.

An educational tidbit can be gathered from Igor and Karl: they are both 105kt storms (as verified by aircraft) yet Igor is about 4 times larger than Karl. With tropical cyclones, it's important to realize that size and intensity are not related. Another contrast is Katrina '05 and Andrew '92... at landfall, Andrew was quite a bit stronger than Katrina (Cat5 vs Cat3), but was a fraction of the size. I cannot resist the opportunity to use a memorable quote from Yoda in Star Wars (Empire Strikes Back): "Size matters not. Look at me. Judge me by my size, do you? And well you should not, for my ally is the Force, and a powerful ally it is."
The area I described yesterday with a surge of southwesterlies continues to look interesting, and more global models are beginning to pick up on possible tropical cyclone formation from it. This area is at about 10-15N and 35-40W.

There's also a potent easterly wave that recently exited the African coast and is now located near the Cape Verde islands. This will be watched closely in the coming days for development as well. The next names on the list are Lisa and Matthew.

16 September 2010

With Karl becoming a hurricane, we have three hurricanes at the same time. This is a pretty rare occurrence. The only other years that this has occurred are 1893, 1926, 1950, 1961, 1967, 1980, 1995, and 1998. 1998 even had four hurricanes at the same time! For those that are interested, the time periods with three hurricanes are as follows:

Igor has not dropped below the CAT4 threshold, and is presently a 120kt storm with a central pressure of 934mb. It is located 910 miles SSE of Bermuda and heading NW at 6kts. It is forecast to maintain major hurricane status through Monday when it begins recurving and interacting with a mid-latitude trough.
The attached file shows the latest suite of model forecasts of Igor's track. There is very little spread among the models, indicating a greater deal of certainty in the forecast. Though not shown on that map, the closest approach occurs 90-96h from the 06Z initialization, which is late Sunday night into early Monday morning. I will make a running radar loop (real-time, accumulating frames) and provide a link to it as the time gets closer.

Julia has entered a more hostile environment as expected, and has weakened... the satellite presentation is much worse today than it was yesterday. As such, the intensity is down to 85kts and 971mb. It is in the open eastern Atlantic, far from anything, and will continue to weaken in the face of increasing vertical shear.

Karl made landfall on the Mexico/Belize border as a 55kt tropical storm, and was barely phased by the flat terrain of the Yucatan peninsula. It exited the peninsula in the early morning hours on Thursday and was very quick to regain its organization. At 15Z today, it was upgraded to a hurricane, the sixth of the season, and is forecast to continue intensifying, perhaps nearly to a major hurricane, before it makes its second and final landfall near Poza Rica on Friday evening. Hurricane Watches and Warnings are in effect, and you can see the latest here: http://www.nhc.noaa.gov/storm_graphics/AT13/refresh/AL1310W5_NL+gif/. The current intensity is 65kts and 983mb and increasing fairly rapidly.

Elsewhere, there is a suspicious surge of southwesterly winds in the area of 5-10N, 30-40W (about 1700 miles east of the Lesser Antilles) and some scattered deep convection associated with the resulting convergence. If that festers for a few more days, a low-latitude tropical disturbance could be in the cards. Something worth keeping an eye on in the coming days, since low-latitude systems are much less likely to recurve before reaching the US.

I'll dedicate today's update to my grandfather, James McNoldy, who passed away this past February, but would be 94 today. He once told a story of his WWII assignment (maintaining and repairing aircraft in Iceland) and the intense storms they'd get there. Once in a while, the remnants of a tropical cyclone make their way up to Greenland, the UK, Portugal, and Iceland, and if you're on an airfield fixing aircraft, you'd notice things like that!

15 September 2010

Igor is still heading WNW and is still a Category 4 hurricane (has been since Sunday afternoon!). The 15Z intensity is 115kts and 942mb, but there was a nighttime intensification period during which it reached 135kts and 925mb... the strongest of its lifetime. It's located about 1055 miles SE of Bermuda and heading WNW at 7kts. In the coming days, Igor's intensity will likely fluctuate but remain very strong, and the track will bend a bit more to the NW. This will bring the hurricane very close to Bermuda by Sunday morning.

Tuesday evening, Julia experienced a period of rapid intensification where the pressure fell 24mb in 6 hours and the wind speed increased 25kts in the same time. As of 15Z, the intensity is 115kts and 950mb. This makes it the forth Category 4 hurricane of the season, and the easternmost CAT4 hurricane on record. Never in recorded history has there been four CAT4 storms so early in the season (we've had Danielle, Earl, Igor, and Julia all by Sept 15). It is also only the second time that two CAT4 storms have existed at the same time (the other time was in 1926). So Julia has certainly become a storm for the record books, as has the 2010 season!

The disturbance that has been tracking through the Caribbean was upgraded to TS Karl at 21Z yesterday based on an aircraft recon flight into the system. Since being named, it quickly intensified to a 55kt storm, and is now inland near the Mexico/Belize border heading W at 12kts. At this rate, it should enter the Bay of Campeche in the early morning hours (local) tomorrow, perhaps as a Depression. It is then forecast to regain TS status and head W into Mexico and make its final landfall early Saturday morning as a TS.

14 September 2010

Igor has weakened slightly to 115kts/945mb, but is still a powerful Category 4 hurricane. During the night, the storm finally made a turn to the WNW, which models have been hinting at for a few days, but the storm wasn't doing it. Assuming this motion continues, this confirms that the storm is feeling the weakness in the subtropical ridge and will continue to turn toward it. Igor is expected to remain a major hurricane at least through this week. The primary land at risk is Bermuda, which could feel the worst of the storm late this weekend.

At 09Z today, Julia was upgraded to the 5th hurricane of the season. In an average season, the 5th hurricane would form around October 7, so we're certainly seeing an active season (the 2nd major hurricane hurricane would climatologically form around October 3, and we've already had 3!). At 15Z, the intensity was estimated at 75kts with a central pressure of 984mb. As is typical for pressures ~985mb, an eye is forming, and Julia is expected to strengthen more, until it hits higher vertical shear in a day or so. It's currently located about 355 miles WNW of the Cape Verde islands and heading WNW at 9kts.

The disturbance that was south of Jamaica yesterday is still not a Depression, and is located south of Isla de la Juventud, Cuba. The appearance continues to improve, and could become a Depression later today. There is a 1006mb Low associated with the disturbance, and the majority of forecast models intensify it to a TS prior to hitting the Yucatan, maintain or slightly weaken it during the crossing, then re-intensify it to a strong TS or weak hurricane as it traverses the Bay of Campeche. Landfall on mainland Mexico is expected on Saturday, assuming a storm actually forms. The next name is Karl.

13 September 2010

Since my previous update on Saturday morning, Igor has become a very powerful Category 4 hurricane, with 130kt winds and a 933mb central pressure. The bulk of the intensification occurred on Sunday, when the pressure fell from 970mb to 942mb in 6 hours (and a corresponding increase in wind speed from 90kts to 120kts). Impressively, it has maintained Cat 4 status for a day now, and isn't showing signs of weakening yet. It's located about 880 miles east of the Leeward islands and heading W at 9kts. The forecast models have consistently been indicating a more NW turn in the track, which so far hasn't happened... in fact, it has been moving slightly south of west over the last 12-18 hours, which only one model (NOGAPS) was predicting. All models, even that one, are now showing a WNW-NW turn beginning almost immediately. There is quite a bit of model variance beyond 3 days, but it also isn't going to affect land any time in the near future.

The strong easterly wave that exited Africa on Saturday was promptly upgraded to TD12 then TS Julia (it was numbered at 21.4W, two degrees east of the easternmost Cape Verde islands... VERY far east!). It is currently located south of the westernmost Cape Verde islands, and the intensity is estimated at 35kts/1004mb. The forecast is for gradual strengthening, probably becoming the season's 5th hurricane, and for a NW turn in the track, taking it into the central Atlantic by 5 days.

The area of disturbed weather that was in the eastern Caribbean on Saturday has not gotten much better organized and is now south of Jamaica. It still has a chance to become a tropical cyclone in the coming days, as it's in a rather favorable environment. The track, if it forms, would be generally WNW into the Yucatan Peninsula then the mainland Mexican coast by the weekend. The next name on the list is Karl.

11 September 2010

Tropical Storm Igor has gone through a few oscillations between sparse and healthy convection, but has maintained a vigorous low-level circulation. As of this writing, the deep convection is located over the center and is fairly symmetric. It appears to be taking advantage of an improving environment and is on its way to becoming the season's 4th hurricane. It's located about 1400 miles east of the Leeward Islands and heading W at 17kts. At 15Z, the intensity was estimated at 60kts and 995mb. The long-range forecast is for Igor to continue heading west, then make a gradual WNW bend by the middle of next week as it passes north of the Leeward Islands.

Two other disturbances are worth watching in the coming days: one in the far eastern Caribbean and one right on the African coast. Both of them are likely to become named storms in the coming days, and the next names are Julia and Karl. The easterly wave that is exiting the African coast is incredibly well-developed and could even be a numbered/named system before reaching the Cape Verde islands!
Also of note: today is the 50-year anniversary of Hurricane Donna's landfall on Florida (Category 4), and Hurricane Iniki's landfall on Hawaii (Category 4).

09 September 2010

Igor is drifting around the Cape Verde islands in very weak steering, and the latest heading estimate is NNW at 5kts, but a general motion to the WNW is expected in the longer term. The deep convection is persistent, but not located over the surface circulation due to the rather strong (~25kts) vertical shear. However, the shear is forecast to drop drastically to about 5kts within the next couple of days and Igor should intensify and become the season's 4th hurricane. At 15Z, the intensity was 35kts and 1006mb. This storm is just off of Africa, so it will be a week or longer until it could even reach the Lesser Antilles, and much longer for any potential US encounter. Here is a map from Jeff Masters showing all past tracks taken by storms in the same location: http://icons-pe.wunderground.com/data/images/at201011_climo.gif

The easterly wave near the Windward Islands continues to get better organized, and is centered very close to Grenada (Grenada suffered catastrophic damage from Hurricane Ivan on Sep 7, 2004 and has barely recovered from that devastation). Luckily, this disturbance is nothing like Ivan, but will still bring flooding rains and perhaps tropical storm force winds to the area. Although poorly organized now, it must be watched very closely because the environment is quite favorable for significant development and forecast track scenarios for a storm in this location inevitably involve at least one landfall. The next name on the list is Julia.

I'd like to thank once again my guest writers during the past week, Kate Musgrave and Gus Alaka. I've heard from some of you that you were quite appreciative to keep receiving these updates in my absence!

08 September 2010

Tropical Depression Hermine (20 kts, 1005 mb) is located in central
north Texas and is bringing heavy rains to much of the state. Most of
the heavy rain occurred to the east of the center, as the onshore flow
helped feed moisture into the system. Much of the region received 3"+
of rain from 12Z yesterday to 12Z today. A few isolated areas (near
Austin, TX) received 10"+ during the same time frame. Hermine should be
extratropical by tonight.
1-Day Rainfall - Texas
<http://water.weather.gov/precip/save.php?layer%5B%5D=0&layer%5B%5D=1&layer%5B%5D=4&timetype=RECENT&loctype=STATE&units=engl&timeframe=current&product=observed&loc=stateTX>
****************************************
A vigorous tropical wave moved off the African coast yesterday. This
system maintained deep convection and the circulation became better
defined. Thus, Tropical Storm Igor, the 9th named storm of the 2010
Atlantic hurricane season, formed in the far eastern Atlantic,
approximately 95 miles SE of the southern Cape Verde Islands. The
initial intensity is set to (35 kts, 1005 mb) and it is currently moving
W at 7 kts. Igor is the 2nd tropical storm to form without first being
a tropical depression (Colin was the other). Presently, tropical storm
watches are out for the southern Cape Verde Islands of Maio, Sao Tiago,
Fogo, and Brava.
Igor's forecast calls for slow strengthening over the next couple of
days, with an increase in motion as it moves generally to the W. NHC
has Igor becoming a hurricane in 72 hours, which is slower than some of
the models, due to the presence of vertical wind shear. Igor is
forecast to turn to the WNW in a few days in response to a weakness in
the subtropical ridge. However, if the ridge does not weaken as
forecast, Igor could be of interest to the Leeward Islands in a week or
so, but let's not get ahead of ourselves.
****************************************
OTHER FEATURES
The remnants of Gaston continue to race through the Caribbean. Although
convection is present with the system, it is quite disorganized. Models
do not call for the redevelopment of this system.

07 September 2010

Earl weakened from a Cat. 1 hurricane to a tropical storm and passed
about 90 miles SSE of Nantucket Island, Massachusetts. Most of the
nasty weather associated with Earl was located to the east of the
center, which allowed SE Massachusetts to escape mostly unscathed.
Nantucket Island experienced gusts to about 55 mph and a few inches of
rain. Earl continued to race to the NE and made landfall at Western
Head, Nova Scotia at 14Z on Saturday with (60 kt, 962 mb). With a large
wind field, much of the province experienced strong tropical storm force
winds and heavy rain. However, Earl had already begun an acceleration
to the NE and did not linger long enough to cause any serious damage.
However, Maritime Electric reported that 9400 Nova Scotian homes were
without power at one point during the storm. Earl quickly raced into
the Gulf of Saint Lawrence, where it was pronounced extratropical at 3Z
on 9/5.
Fiona continued to weaken and bear down on Bermuda late last week.
However, the unfavorable environmental conditions got the best of the
system, and Fiona degenerated into a remnant low before reaching
Bermuda. At the last advisory, Fiona was only 60 miles south of
Bermuda. The island likely experienced some gusty winds and isolated rain.
TD10 formed in the SW Gulf of Mexico late Sunday evening. By Monday
morning, TD10 intensified into Hermine, the 8th Atlantic tropical storm
of 2010. Moving generally to the NNW, Hermine intensified from (35 kt,
1001 mb) at 9Z to (55 kt, 991 mb) at 0Z. Hermine was still intensifying
at landfall, and if the track had been slightly more N (rather than
NNW), Hermine may have had a chance to become the 4th hurricane of the
Altantic basin. Hermine has since moved inland and will bring heavy
rains (4"-8") and flooding to south Texas as the center moves to the N
at ~15 kts. Hermine, still a minimal tropical storm, is forecast to
continue weakening and should be a tropical depression at the next
advisory.
I was able to find this Doppler Radar image of Hermine at landfall:

There are no other named storms or depressions in the Atlantic.
However, there are a few features of interest.
The remnant low of Tropical Storm Gaston is entering the NE Caribbean.
There has been some convection associated with the remnant low, although
NHC does not expect further development from this system. To provide
more support to NHC's assertion, a number of models (GFS, ECMWF,
GFDL...) do not redevelop Gaston either. Nonetheless, this system will
be monitored for any signs of organization.
A potent tropical wave has just exited the west African coast. It will
be monitored for development as it travels W.

03 September 2010

Hurricane Earl passed east of NC early this morning as a Category 2 hurricane, before weakening further to a 75kt/961mb Category 1 hurricane at the 15Z advisory. Earl is currently located about 175 miles NE of Cape Hatteras, NC, or about 350 miles SSW of Nantucket, Mass. Earl continues to move NNE at 18kt and is expected to approach Cape Cod tonight as a hurricane, and reach Nova Scotia, Canada as a tropical storm tomorrow morning, before going extratropical in about 36 hours. Hurricane warnings remain in effect for parts of the Mass coast, with hurricane watches for parts of the southern coast of Nova Scotia. Tropical storm warnings range from NC to NJ, and parts of Long Island through portions of Mass, with tropical storm watches and warnings posted in Maine, New Brunswick and Nova Scotia. While Earl has weakened significantly, from 120kt to 75kt in 24 hours, the area covered by tropical storm strength winds is extensive, up to 205 miles from the center of the system.

Tropical storm Fiona has continued to recurve and weaken as it approaches Bermuda. As of 15Z it is 40kt/1010mb, moving NNE at 11kt. Fiona is expected to continue its weakening trend, dissipating within 3 days. It's center should pass closest to Bermuda in about 18 hours.

Tropical depression Gaston continued to weaken yesterday, dropping from a depression to a remnant low. The area will be monitored for possible redevelopment over the next few days. It is still expected to move to the W/WNW, approaching the Lesser Antilles in about a week.

02 September 2010

Hurricane Earl has re-strengthened into a Category 4 hurricane, with its intensity at 15Z estimated at 120kt/932mb. Hurricane warnings continue on the NC coast and have been issued for parts of the Mass coast. Hurricane watches extend from the NC/VA border up through DelMarVa peninsula. Tropical storm warnings extend from the NC/VA border up to Mass, with tropical storm watches for parts of Long Island and extending from Mass up through Maine and parts of Nova Scotia, Canada. It is expected to weaken in intensity as it approaches the North Carolina coast, but still be a major hurricane at its closest approach overnight tonight/early Friday morning. Earl is expected to then accelerate and turn towards the NE, bringing it close to Mass by Friday night and then approaching Nova Scotia Saturday.

Tropical Storm Fiona has weakened slightly over the past day, and begun turning more to the N. As of 15Z it is estimated at 45kt/1002mb, moving NNW at 15kts. Fiona is expected to continue recurving to the N and NE, heading towards Bermuda. Tropical storm warnings have been posted for Bermuda. Fiona continues to deal with a much less favorable environment than Earl's, and the official forecast continues weakening Fiona before dissipating it in 4 days.

TD9 strengthened into Tropical Storm Gaston yesterday at 21Z, before dropping back down to a depression at 15Z today. It is currently about 1600 miles east of the Lesser Antilles and has slowed its forward motion. As of 15Z it is estimated at 30kt/1008mb, heading WNW at 6kts. It is expected to track WNW over the next several days and is still a week away from the Lesser Antilles, with the majority of models bringing it to hurricane intensity within that time.

01 September 2010

Earl has weakened very slightly, and just happened to cross the Cat 3-4 threshold to 110kts (943mb central pressure). It's currently located about 725 miles SSE of Cape Hatteras, NC and heading NW at 14kts. Hurricane Warnings now cover all of the NC coast and Hurricane Watches cover the southern parts of the VA coast and the DelMarVa peninsula. The closest approach to the coast is expected early Friday morning, still as a major hurricane. Even if a direct landfall doesn't occur (meaning the center of the eye crosses the coastline), the western half of the storm, and perhaps even the eyewall, will affect land with flash flooding, strong damaging winds, and major beach erosion. Coastal areas from central NC up to Cape Cod can expect some storm surge, generally in the 2-5' range.

Tropical Storm Fiona has been improving in satellite appearance, but not drastically. It's approaching the northern Leeward Islands, but will steer away toward the NW before affecting them as much as Earl did 2-3 days ago. Its environment is much less favorable than Earl's was at the same location, and the official forecast actually weakens the storm to a Depression in 5 days as it recurves and heads n toward Bermuda. At 15Z, the intensity is 50kts and 998mb.

Elsewhere, an easterly wave that exited the African coast on the 28th has gradually been getting better organized, and has been upgraded to TD9. The majority of models develop this system into TS/Hurricane Gaston. It's about 1800 miles east of the Windward Islands, moving W at 13kts, and the intensity is estimated at 30kts/1006mb. It will track to the WNW over the next several days... still a week away from the Lesser Antilles.

I'd like to introduce a couple 'guest writers' who volunteered to send these updates out while I'm on vacation for the next week. Kate Musgrave and Gus Alaka, both very knowledgeable colleagues here at CSU, will keep you up-to-date with the activity across the basin. Thanks in advance to Kate and Gus!

Author: Brian McNoldy,Senior Research Associate at University of Miami's Rosenstiel School of Marine and Atmospheric Science

"In the eye of a hurricane, you learn things other than of a scientific nature. You feel the puniness of man and his works. If a true definition of humility is ever written, it might well be written in the eye of a hurricane." -Edward Murrow, reporting on Hurricane Edna 1954